This project is aimed at determining the expression patterns and the roles of CaMKII in the formation and function of mouse olfactory bulb. The normal expression patterns of CaMKII are essential for understanding this enzyme's functional roles. We will first use the CaMKII specific antibodies to determine where CaMKII is expressed in the mouse olfactory bulb. CaMKII immunoreactive neurons will be further characterized by double labeling with antibodies specific for GABA or glutamate. The ultrastructural location of CaMKII will be determined by electron microscopy, particularly we will examine whether CaMKII is expressed in the reciprocal dendroendritic synapses that are characteristic of the olfactory bulb. In order to understand how CaMKII might function in the olfactory system, we propose to modulate CaMKII activity in the bulb either by using a CaMKII knockout mouse or by expressing active CaMKII or CaMKII inhibitor with Sindbis viruses. In particular, we will investigate whether CaMKII activity regulates the development of granule cells, the most abundant neurons in the olfactory bulb.